Paper: Improving the Exact Security of Digital Signature Schemes

We provide two contributions to exact security analysis of
digital signatures:
We put forward a new method of constructing Fiat-Shamir-like
signature schemes that yields better "exact security" than the original
Fiat-Shamir method; and
we extend exact security analysis to "exact cost-security analysis" by
showing that digital signature schemes with "loose security" may be
preferable for reasonable measures of cost.